import java.util.LinkedList;
import java.util.Queue;
class TreeNode {
    public char val;
    public TreeNode left;//左孩子的引用
    public TreeNode right;//右孩子的引用

    public TreeNode(char val) {
        this.val = val;
    }
}

class BinaryTree {
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
        A.left =B;
        A.right=C;
        B.left=D;
        B.right=E;
        C.left=F;
        C.right=G;
        E.right=H;
        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root==null){
            return;
        }
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root==null){
            return;
        }
        preOrder(root.left);
        System.out.print(root.val+" ");
        preOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root==null){
            return;
        }
        preOrder(root.left);
        preOrder(root.right);
        System.out.print(root.val+" ");
    }

    public static int Size;

    void nodesize(TreeNode root) {
        if(root==null){
            return;
        }
        nodesize(root.left);
        Size++;
        nodesize(root.right);
    }

    int nodesize2(TreeNode root) {
        if(root==null){
            return 0;
        }
        return  nodesize2(root.left)+nodesize2(root.right)+1;
    }
    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root==null){
            return;
        }
        if(root.left==null&&root.right==null){
            leafSize++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if(root==null){
            return 0;
        }
        if(root.left==null&&root.right==null){
            return 1;
        }
        return getLeafNodeCount2(root.left)+getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        if(root==null){
            return 0;
        }
        if(k==1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1)
                +getKLevelNodeCount(root.right,k-1);
    }
    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if(root==null){
            return 0;
        }
        int leftHeight = getHeight(root.left);
        int rightHeight = getHeight(root.right);
        return leftHeight>rightHeight?leftHeight+1:rightHeight+1;
    }


    // 检测值为value的元素是否存在
    boolean find(TreeNode root, char key) {
        if(root==null){
            return false;
        }
        if(root.val==key){
            return true;
        }
        boolean leftVal = find(root.left,key);
        if(leftVal==true){
            return true;
        }
        boolean rightVal = find(root.right,key);
        if(rightVal==true){
            return true;
        }
        return false;
    }

    //层序遍历
    void levelOrder(TreeNode root) {
        if(root==null){
            return;
        }
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            TreeNode cur =queue.poll();
            System.out.print(cur.val+" ");
            if(cur.left!=null){
                queue.offer(cur.left);
            }
            if(cur.right!=null){
                queue.offer(cur.right);
            }
        }
    }
}

public class Test {
    public static void main(String[] args) {
        BinaryTree binaryTree = new BinaryTree();
        TreeNode root = binaryTree.createTree();
        System.out.println(binaryTree.nodesize2(root));

    }
}
